first commit

src/main.js

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+(function (Scratch) {
+    'use strict';
+
+    // 非沙箱守卫：确保扩展有权限发起网络请求
+    if (!Scratch.extensions.unsandboxed) {
+        throw new Error('S3 扩展必须运行在非沙箱模式下');
+    }
+
+    class S3Extension {
+        constructor() {
+            // 在内存中保存凭据（仅用于演示，生产环境需注意安全）
+            this.credentials = {};
+        }
+
+        getInfo() {
+            return {
+                id: 's3client',
+                name: 'S3 客户端',
+                blocks: [
+                    {
+                        opcode: 'setCredentials',
+                        blockType: Scratch.BlockType.COMMAND,
+                        text: '设置 S3 凭据 Key [AK] Secret [SK] 区域 [REGION]',
+                        arguments: {
+                            AK: { type: Scratch.ArgumentType.STRING, defaultValue: 'AKIA...' },
+                            SK: { type: Scratch.ArgumentType.STRING, defaultValue: 'secret...' },
+                            REGION: { type: Scratch.ArgumentType.STRING, defaultValue: 'us-east-1' }
+                        }
+                    },
+                    {
+                        opcode: 'putObject',
+                        blockType: Scratch.BlockType.COMMAND,
+                        text: '上传桶 [BUCKET] 键 [KEY] 内容 [BODY]',
+                        arguments: {
+                            BUCKET: { type: Scratch.ArgumentType.STRING, defaultValue: 'my-bucket' },
+                            KEY: { type: Scratch.ArgumentType.STRING, defaultValue: 'hello.txt' },
+                            BODY: { type: Scratch.ArgumentType.STRING, defaultValue: 'Hello S3!' }
+                        }
+                    },
+                    {
+                        opcode: 'getObject',
+                        blockType: Scratch.BlockType.REPORTER,
+                        text: '下载桶 [BUCKET] 键 [KEY]',
+                        arguments: {
+                            BUCKET: { type: Scratch.ArgumentType.STRING, defaultValue: 'my-bucket' },
+                            KEY: { type: Scratch.ArgumentType.STRING, defaultValue: 'hello.txt' }
+                        }
+                    }
+                ]
+            };
+        }
+
+        setCredentials(args) {
+            this.credentials = {
+                accessKey: args.AK,
+                secretKey: args.SK,
+                region: args.REGION
+            };
+        }
+
+        // 这里接入上一轮实现的 SigV4 签名与 fetch 调用
+        async putObject(args) {
+            const { accessKey, secretKey, region } = this.credentials;
+            // 1. 计算 payload hash（对 BODY 做 SHA256）
+            // 2. 构造 CanonicalRequest -> StringToSign -> Signature
+            // 3. fetch(`https://${args.BUCKET}.s3.${region}.amazonaws.com/${args.KEY}`, { method: 'PUT', ... })
+            // 返回成功或抛出错误
+        }
+
+        async getObject(args) {
+            // 签名时 payload hash 为空字符串的 SHA256
+            // fetch GET，返回 res.text() 或 arrayBuffer
+        }
+    }
+
+    Scratch.extensions.register(new S3Extension());
+})(Scratch);